The present invention relates to an image pickup apparatus and system that photographs an object to output a video signal, and in particular, to an image pickup apparatus with a separated image pickup section in which the image pickup section and a signal processing section are connected together via a cable or by radio as well as an image pickup system using this apparatus.
FIG. 28 is a block diagram showing a system configuration of a conventional general image input apparatus. In this figure, numeral 301 denotes a system control section for controlling the entire system; numeral 303 denotes an optical lens system including a zoom lens, a zoom motor that drives the zoom lens, a focus lens, and a focus motor that drives the focus lens; numeral 304 denotes an iris that adjusts the amount of incident light passing through the optical lens system 303; numeral 305 denotes a CCD that is an image pickup element; and numeral 306 denotes a timing generator (hereafter referred to as a xe2x80x9cTGxe2x80x9d) for controlling the CCD 305.
Reference numeral 307 denotes an S/HandAGC circuit for performing a sampling and holding operation to reduce noise from stored charges in the CCD 305 and adjusting the gain of an image pickup signal; numeral 308 denotes an A/D converter for converting an analog signal from the S/HandAGC circuit 307 into a digital signal; numeral 309 denotes a signal processing circuit for executing required signal processing to convert a digital signal from the A/D converter 308 into a video signal to output various information required to control auto-focus (AF), auto-exposure (AE), and auto-white-balance (AW).
The image input apparatus is integral and comprises an image pickup section and a signal processing section that are integrated together. The system control section 301 comprises a control data sampling module for sampling control data from the signal processing circuit 309, an AF control module, an AE control module, and an AW control module.
In such a conventional integral image input apparatus, the system control section 301 obtains various control data from the signal processing section 309 (the control data sampling module) and based on this information, controls the zoom control module for controlling the zoom lens in the system control section 301, the AF control module for controlling the focus and the AE control module for controlling the iris 304, TG 306, and S/HandAGC circuit 307 to maintain the signal level at a constant level.
The present day is called the xe2x80x9cmultimedia agexe2x80x9d and the image input apparatus is used for various applications. One example is a television conference system. Image input apparatuses used for such a system have different functions for different applications. For example, a single focus camera is sufficient to photograph a single person while a camera with a tripod head or a zoom lens is required to photograph several people.
In the above conventional example, however, since the camera section that is the image pickup section is integrated with the camera signal processing section, all components of the image input apparatus must be replaced when it is used for different applications.
In view of this point, for an image pickup apparatus using a charge coupled device (hereafter referred to as a xe2x80x9cCCDxe2x80x9d) as an image pickup element, an apparatus called a head-separated camera has been proposed in which an image pickup section including a CCD and a signal processing section for processing a video signal from the CCD to output it as a video signal are separated from each other and connected to each other via a cable.
With the improvement of recent electronic technology, the size and weight of camera apparatuses using the CCD are being reduced. In particular, the improvement of semiconductor technology has contributed to the development of apparatuses for executing the A/D conversion of a video signal at a high speed and using a DSP (a Digital Signal Processing circuit) to process and output the digitalized video signal.
Such conventional head-separated cameras, however, require a large number of signal lines used to transmit video signals, various synchronizing signals in synchronism with the video signals, and various control commands for panning, tilting, and zooming the camera, between the camera head section and the signal processing section. In addition, the camera head section typically has no power supply unit for supplying electric power, so these cameras require a power supply line for supplying power from the signal processing section as well as the signal line described above.
In addition, if an attempt is made to separate the image pickup section from the image processing section with the VCR circuit configuration unchanged, control data transmitted between a controller for the image pickup section and a controller for the signal processing section will leak into a video signal to degrade it.
To avoid this condition, tight shielding can be provided to prevent signals from affecting each other but this requires a thick and hard cable to connect these sections together, resulting in degraded usability.
FIG. 29 shows a configuration of a conventional camera section (an image pickup section) 1.
In FIG. 29, the camera section 1 has a zoom lens 10; an iris 11; an optical lowpass filter and infrared cut filter 12; a CCD 13; a CDS circuit 14; an AGC circuit 15; an addition circuit 16 for adding a CCD signal, a composite synchronizing signal, and a burst clock together; a drive circuit 17 for driving, for example, a 75-xcexa9 coaxial line 2: a synchronizing signal generator (SSG) 19; an MPU micro processing unit 20 for controlling the entire camera section 1; and a burst gate (BG) circuit 18 for applying a gate to add a burst clock to a video signal.
The cable 2 connects the camera section 1 to an image processing section (a signal processing section) 3, which is described below.
Reference numeral 30 denotes a terminal for outputting a video signal to which a clock and a composite synchronizing signal are added; numeral 31 denotes a terminal for outputting a transmit signal used to communicate with the image processing section 3; and numeral 32 denotes a terminal for inputting a receive signal used to communicate with the image processing section 3.
The operation is described with reference to FIGS. 29 to 31. A CCD image pickup signal (a video signal) is obtained via the zoom lens 10, iris 11, optical lowpass filter and infrared cut filter 12, CCD 13, CDS circuit 14, and AGC circuit 15. The synchronizing signal generator 19 outputs various synchronizing pulses and composite synchronizing signals used for CCD photographing, burst gate pulses (BGP), and a clock used as a reference for photographing. Based on the BGP from the synchronizing signal generator 19, the burst gate (BG) circuit 18 executes gating so as to change a continuously input clock into a burst clock suitable for addition to a video signal. The addition circuit 16 adds together a video signal output from the AGC control circuit 15, a burst clock from the BG circuit 18, and a composite synchronizing signal from the synchronizing signal generator 19. After addition, the video signal is driven by the 75-xcexa9 drive circuit 17 and output to the image processing section 3 from an output terminal 30. FIG. 30 shows part of a video signal to which a burst clock and a composite synchronizing signal are added. xe2x80x9cAxe2x80x9d shows a composite synchronizing signal, xe2x80x9cBxe2x80x9d shows a burst clock, and xe2x80x9cCxe2x80x9d shows a video signal area. The MPU 20 uses an output terminal 31 and an input terminal 32 to communicate with an MPU in the image processing section 3 in order to drive the zoom and auto-focus lenses and to control the iris and AGC.
FIG. 31 shows a configuration of a conventional image processing section 3. The image processing section 3 is shaped like an extension board of a computer and inserted into an extension board slot in the computer.
The image processing section 3 has a buffer circuit 39 for a video signal 30; a clamp circuit 40; an AD converter 41; a digital signal processing (DSP) circuit 42 for executing digital signal processing such as filtering, color separation, gamma correction, matrix operation, or clipping; a DA converter 43 for executing the digital-analog conversion of a digitalized signal to output a video signal (for example, NTSC); an MPU 48 for controlling the entire image processing section 3; a synchronization separation circuit 44; a synchronizing signal generator 45; a band path filter (BPF) 46; a burst gate (BG) circuit 47, and PLL (Phase Locked Loop) circuit 49.
Reference numeral 30 denotes a terminal for inputting a video signal to which a clock and a composite synchronizing signal are added; numeral 31 denotes a terminal for inputting a receive signal used to communicate with the camera section 1; and numeral 32 denotes a terminal for outputting a transmit signal used to communicate with the camera section 1.
The operation in FIG. 31 is described. A video signal that has passed through the buffer circuit 39 and clamp circuit 40 is input to the AD converter 41, synchronization separation circuit 44, and the band path filter (BPF) 46. The synchronization separation circuit 44 generates from the input video signal an HD (horizontal synchronization) signal, a VD (vertical synchronization) signal, and a burst gate pulse (BGP). The HD and VD signals are input to reset terminals of a horizontal and a vertical synchronization counters (not shown) in the synchronizing signal generator 45 to provide horizontal and vertical synchronization with the camera section 1. The HD and VD signals in synchronism with the camera section 1 are input to the DSP circuit 42. After the video signal has been input to the BPF 46, almost all of the synchronizing signal and video signal are attenuated to allow only frequencies near the burst clock to pass through. After passing through the BPF 46, the signal is input to the BG circuit 47, where based on a BGP generated by the synchronization separation circuit 44, noise components remaining in the video signal are removed from the signal to extract only the burst clock, which is then input to the PLL circuit 49. The PLL circuit 49 comprises a phase comparison circuit (PC) 50, an LPF 51, and a voltage control oscillator (VCO) 52, and generates from the burst clock a clock (CLK) with a matching phase to output it to the synchronizing signal generator 45, AD converter 41, and DSP circuit 42. The video signal, which has been input to the AD converter 41, is converted into a digital signal, image-processed by the DSP circuit 42 in synchronism with a clock from the PLL circuit 49 and a synchronizing signal from the synchronizing signal generator 45, and then converted into an analog video signal (for example, an NTSC signal) by the DA converter 43 for output. In addition, the MPU 48 is electrically connected to a computer PC via a bus BUS and bidirectionally communicate in response to commands from the PC. The MPU 48 uses the output terminal 32 and the input terminal 31 to communicate with the MPU 20 in the camera section 1 in order to drive the zoom and auto-focus lenses and to control the iris and AGC.
Such a separated camera is characterized by the small size and weight of the camera section 1 and is advantageous in that the camera section 1 can be replaced depending on the application. For example, the image processing section 3 can be used in common while the camera section 1 can be changed, for example, between a single-focus camera and a zoom camera depending on the application.
This configuration, however, allows camera sections each including a CCD having the same number of pixels (resolution) to be replaced with each other, but if camera sections each including a CCD having a different number of pixels are replaced with each other, the image processing section 3 cannot reproduce a clock. This is due to the difference in clock frequency, which prevents the correspondence of the filter frequency when a burst clock is extracted from a video signal. That is, the conventional configuration does not allow replacement with a camera that uses a CCD having a different number of pixels.
In addition, one example of such an image pickup system is a television conference system. Most of such television conference systems can be classified into a larger conference room type that is housed in a cabinet and a cart type that is housed in a cart with wheels. With the recent spread of personal computers, however, attention has been paid to desk top conference systems using a personal computer. This system is composed of a video camera 9101; a personal computer extension board 9102 that obtains sounds and images, that compresses and expands data, and that executes communication; and software 9104, as shown in FIG. 32.
FIG. 33 is an outline drawing showing a desk top television conference system that uses the components 9101 to 9104 in a personal computer. In this figure, numeral 9105 denotes a personal computer body, numeral 9106 denotes a personal computer monitor, numeral 9107 denotes a keyboard, and 9108 denotes a mouse. FIG. 34 shows a state in which these components are electrically connected together. In this figure, the video camera 9101 has, for example, a tripod head and also has a video output terminal, an S video output terminal, an audio line output terminal, a DC power supply input terminal, and an RS232C control terminal. First, to supply DC power to the video camera 9101, DC power supply lines (a DC power supply and a ground lines) 9110 are connected to the video camera via an AC adapter 9109. Next, among the image outputs from the video camera 9101, for example, the S video output terminal is connected to an S video input terminal of the personal computer extension board 9102 via a video cable 9111. Then, an RS232C cable 9113 is used to connect an RS232C terminal of the personal computer body 9105 to an RS232C terminal of the video camera in order to control various functions for panning, tilting, and zooming the video camera.
Thus, the electric connections relating to the (1) power supply to the camera, the (2) video signal, and the (3) control signal have been finished, and after turning the power supply to the personal computer on, predetermined software can be driven to allow the apparatus to function as a desk top television conference system.
The connection cables used for the above electric connections can be summarized as follows.
(1) Two lines for the DC power supply lines 9110, i.e., one for DC power supply line and another for GND line.
(2) Four lines for the video cable 9111, i.e., one for Y video signal line, one for C video signal line, and two individual GND lines.
(3) Eight lines for the RS232C cables. For synchronous serial communication, only four lines including a TX line, an RX line, a clock line, and a GND line are required.
On the other hand, a head set having a conductive tripod head requires another cable between the head set and the extension board 9102. Thus, 3 types of cables and at least 9 signal lines are required.
The above conventional example has the following problems.
(1) The power supply cable 9110, video cable 9111, and RS232C cable 9113 are separately connected to the video camera 9101, thereby degrading the appearance of the camera and its reliability. That is, the disconnection of any one cable may result in an operational problem.
(2) Since the video cable 9111 and a cable for a head set with a tripod head are separately connected to the personal computer extension board 9102, the rear of the personal computer body 9105 on which the connections of these cables are provided also degrades the appearance of the body.
(3) The RS232C cable 9113 for controlling the video camera 9101 is connected to the RS232C terminal of the personal computer body 9105. This connection, however, is not preferable because this terminal may need to connect to other device such as a modem or printer.
(4) It is necessary to confirm that AC power is provided to the AC adapter 9109 and also to confirm that AC power is provided to the personal computer body 9105, and there are two AC power cables.
It is an object of this invention to provide an image pickup apparatus and system that can solve these problems.
It is another object of this invention to provide an image pickup apparatus and system that enables an image pickup section to be replaced with one with a different resolution.
It is still another object of this invention to provide an image pickup apparatus and system that superposes control data transmitted from a camera section to an image processing section, on a video signal on which a synchronizing signal and a clock are superposed, thereby reducing the number of communication cables between the camera section and the image processing section.
It is still another object of this invention to provide an image pickup apparatus that is preferably used for, for example, a television conference system and an image pickup system to which an image processing apparatus for processing photographed images is connected.
It is still another object of this invention to provide an image pickup apparatus and system that superposes a power supply line for supplying electric power from the image processing section to the image pickup unit, on a signal line paired with a signal line that superposes various synchronizing signals and a video signal, thereby reducing the number of lines between the image pickup unit and the image processing unit.
It is still another object of this invention to provide an image pickup apparatus and system that multiplexes a video signal, various synchronizing signals, and transmit and receive data to transmit the multiplexed signal via a signal line and that superposes a power supply voltage on a signal line that is paired with the above signal line, thereby reducing the number of lines.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.